This invention relates to liquid containers and more particularly to field erected storage tanks that are adapted to being dismantled after they have been used, moved to another location, and then erected again. Such tanks are ordinarily made from standard sheet metal or corrugated panels that are bolted together to form an upstanding peripheral wall which is not capable of containing a liquid. To hold the liquid in the tank, a sheet of plastic or other liquid impervious material is placed along the inside of the tank wall and on top of the ground or foundation within the wall. Such liners are frequently damaged by sharp or irregular objects or areas on the tank wall, such as bolt heads and the wall's peripheral edges, and by objects on the ground. Also, as the tank is filled with and emptied of liquid, and as wind and other loads on the tank change the stresses on the liner, it can be damaged by rubbing against the tank wall and by streching or bunching up. Prior attempts to protect the liner from such damage have been complicated or have required special tank or liner structure. Also, it has been suggested that dirt be piled up to form a cove at the bottom of the tank to protect the liner where it bends to go up the tank wall. This has not been satisfactory because the dirt cover may fall away from the tank wall as the liner is shifted into place, or it may settle and cause stress on the liner walls, seams, or base; also the dirt may contain sharp objects, or may itself be abrasive enough, to damage the liner.